The present invention relates generally to gas generating systems and, more particularly, to gas generators used in vehicle occupant protection systems and related components, such as seatbelt pretensioners.
Gas generators used in seatbelt pretensioners are known as micro gas generators (MGG's) due to the relatively small size of the gas generator. Exemplary pretensioners using such micro gas generators include those described in U.S. Pat. Nos. 6,460,794, 6,505,790, 6,520,443, and 6,419,177, incorporated herein by reference. Micro gas generators generally include a bore seal for receiving and securing an initiator therein, an initiator including an initiator charge, and a gas generant composition which ignites and burns in response to activation of the initiator to produce gases for actuating the seatbelt pretensioner.
A portion of the bore seal is configured to mate with a mating connector element formed on a portion of a vehicle to which the initiator assembly is attached. Typically, the bore seal is formed from a metal, such as steel or aluminum. Mating features (such as slots and undercuts) and other desired features are machined into appropriate surfaces of the metal bore seal. However, machining these features into the bore seal is relatively expensive. Some existing micro gas generator designs incorporate an initiator assembly in which the initiator is molded into a bore seal formed from a plastic material to include the desired mating features. However, limitations on molding process temperatures and pressures imposed by the structure of the initiator tend to limit the range of plastics suitable for insert molding. This results in a bore seal having insufficient strength for micro gas generator operation.